My project is based on the topic of "Old Salty: Does age affect the ability to detect salt?". My question is what are the controlled variables in this experiement and how will they be held contant throughout? Also, what may be a better rating system that could be used in this experiement?

Project Question: My project is based on the topic of "Old Salty: Does age affect the ability to detect salt?". My question is what are the controlled variables in this experiement and how will they be held contant throughout? Also, what may be a better rating system that could be used in this experiement?

Upon reviewing the description of this project I can see that the primary controlled variable is the salt concentration in the three salt solutions you prepare.

Other controlled variables should be the temperature of the salt solution when your specimens drink it. That should remain constant for all tests. Room temperature should be fine. Just make sure you measure that temperature for each test.

I think the rating system is quite adequate the way it is described in the project description. Do you have a specific concern about the rating system?